Method and composition for detecting leaks in refrigerating systems



. from leaks, even minute ones.

Patented June 27, 1933 UNITED. STATES PATENT OFFICE HARE? M. WILLIAMS, OF DAYTON, OHIO, ASSIGNOR TO FBIGIDAIQE CORPORATION, DAYTON, OHIO, A CORPORATION OF OHIO METHOD AND COMPOSITION FOR DETECTING LEAKS IN REFRIGERATING SYSTEMS N0 Drawing.

My invention relates to chemistry and more particularly to methods of testing apparatus suspected of leakage. It is especially concerned with methods of testing for leaks in a refrigerating system of the compression type.

In refrigerating apparatus of the compression type, refrigeration is produced by the evaporation of a volatile liquid, the vapors being compressed in a compressor, condensed in a condenser and again permitted to evaporate within the evaporator. A lubricant is used within such apparatus for sealing and/or lubricating the wearing surfaces. In some compression systems, the lubricant is deliberately carried throughout the complete cycle while in other systems, attempts are made to separate the lubricant from the refrigerant by means of an oil separator generally positioned on the high pressure side and designedto substantially prevent the passage of lubricant into the evaporator. Even in this last named system, some lubricant will pass the separator and will be carried along with the refrigerant through the complete cycle. Thus in all compression refrigerating systems, some lubricant will be present in all parts of the system at substantially all times.

It will be appreciated that it is essential for refrigerating apparatus to be quite free Otherwise, either the refrigerant and/or lubricant will gradually escape, or else air will gradually leak into the apparatus. In either event, the apparatus will gradually produce less and less refrigerating effect, although it apparently is working perfectly in every other respect. Consequently, it is necessary that the apparatus be thoroughly subjected to tests which willshow the existence of the smallest leak before such apparatus is installed and occasionally after the installation of such apparatus. It will also be appreciated that such tests must be of a simple nature for use in the field and inexpensive to perform, particularly where apparatus is manufactured under quantity production.

Many refrigerants are, however, quite difficult to detect because they do not react with Application filed May 29, 1931. Serial No. 541,123.

the well known and commercially available reagents: to give either a color, fum1ng,'or

odor test. Examples of such refrigerants are way diluting or otherwise affecting the properties of the refrigerants.

In carrying out my process for testing re-' frigerating apparatus for leaks, make use of the property of basic dyes to permanently. stain certain surfaces. For example, I have foundthat certain basic dyes such as methyl violet base, crystal violet, auramine. B, rhodamine B, etc.-have the property of perma nently staining certain materials .such as titanium oxide,silica,asbestos, mica, zinc oxide, magnesium oxide, frost, aluminum oxide, aluminum palmitate, and salts such as tri-basic calcium phosphate.

Thus, by coating the apparatus with a paint containing one or more of the above or similar substances, it is possible to obtain a permanent stain by permittinga basic dye to escape from the leaking apparatus.

As a specific example of one mode of carrying out my invention in a refrigerating system using CClgFg asthe refrigerant and mineral oil as the lubricant, I dissolve a small amount of basic dye, such as methyl violet base, in the mineral oil. This solution is obtained by first dissolving the methyl violet base in alcohol or other suitable solvent and then mixing and stirring the solution with the mineral oil, or by mixing the methyl violet base directly with the lubricant and stirring the mixture. The refrigerating system is then charged with its usual amount of (301 15 and mineral oil having the methyl violet base dissolved therein.

The refrigerating apparatus, and particularly those parts where leaks are likely to occur, are painted with a paint such as Duco containing titanium oxide, silica or any other I will indicate a leak which is then specifical- 1y detected by the stain.

After the leak has been detected and re-.

paired, the stain may be removed by painting over with the paint.

The other basic dyes may be used by dissolving the dye in the oil in substantially the same manner.

Likewise, other materials. such as those indicated above, may be used for detecting purposes. For example, the entire refrigerating apparatus may be dipped in aluminium pallnitate or the apparatus may be painted where leaks are likely to occur, with paint containing magnesium or aluminium oxide. Also, any of the other halo-fluoro derivatives may be used as the refrigerant and, in fact, any refrigerant which does not have the property of bleaching the color deposited by the basic dye.

It will be apparent, therefore, that I have rovided a very economical and simple test gor leaks in a refrigerating system. By painting or otherwise treating the parts of the apparatus as manufactured or the apparatus as assembled, no additional appa'ratus is necessary for the process.

Basic'dyes as purchased on the market frequently contain dextrine or other substance for standardizing purposes. It is advisable to utilize in my method, a basic dye free of dextrine or other filler.

While I have disclosed various dyes, substances capable of being stained, refrigerants, and lubricants, it should be understood that my invention involves the useof a dye capable ofpermanently staining certain surfaces with any refrigerant that does not destroy the permanent color imparted to the stainable substance.

What is claimed is as follows:

1. In refrigerating apparatus using as a working fluid both a refrigerant and a lubricant, the method of detecting leaks which comprises dissolving a basic dye in the lubricant, treating the apparatus with a material stainable with the basic dye, and staining the material at the point of leakage.

2. In refrigerating apparatus using a halofluoro derivative of an aliphatic hydrocarbon as the refrigerant and an oil, the method of detecting leaks which comprises dissolving a basic dye in the lubricant, treating the apparatus with a material stainable with the basic dye, and staining the material at the leak.

3. A working fluid for refrigerating sy s- J In testimony whereof I hereto aflix my signature.

HARRY M wILLIAMs. 

